This invention relates to heat exchangers including charge air coolers such as those used for vehicles.
It is known to provide heat exchangers in the form of charge air coolers that have opposing inlet and outlet collection tanks or manifolds fluidly connected by tubes that direct the charge air from the inlet tank or manifold of the cooler to the outlet tank or manifold. A recent example of such a cooler is that taught in U.S. Pat. No. 6,755,158 issued Jun. 29, 2004 to Modine Manufacturing Company. This particular charge air cooler has a coolant-filled pre-cooler oriented in the air collection tank. The pre-cooler is sized to contact most of the charge air entering the cooler. The pre-cooler has flow paths carrying coolant between manifolds of the pre-cooler and the flow paths define channels therethrough to direct charged air through the pre-cooler and into a cooling grate.
Another example of a charge air cooler is that taught in German published application 3200688 A1 wherein a second heat exchanger unit has inflow and outflow lines or manifolds with flat tubes extending between these two manifolds. The tubes of the second heat exchanger are in parallel arrangement to air cooled tubes. Cooling of the charge air takes place by heat exchange between the charge air and cooling air. In the illustrated embodiment, there are three alternating layers in the complete air cooler. These layers including vertically extending tubular passageways for charge air, the vertically extending tubes for the coolant, and layers for the passage of cooling air horizontally through the heat exchanger.
It is foreseen that the exhaust limits of vehicles, particularly those with diesel engines, will place larger demands on heat exchangers. There may be a need for the temperature of charge air exiting the charge cooler to be reduced much further than previously even though the charge air entering the charge cooler will have a much higher temperature than previously. These new parameters for air charge coolers should, if possible, be met without requiring significantly larger design space for the charge air cooler.
It is therefore desirable to provide a heat exchanger such as a charge air cooler which is able to provide additional means for cooling a first heat exchanging fluid, such as charge air, in addition to the normal cooling air flowing through the heat exchanger, this additional means taking the form of an associated cooling device for circulating a liquid coolant for heat exchange between the coolant and the first fluid this cooling device being located to a significant extent within the area occupied by the normal heat exchanger components. It is further desirable if such a heat exchanger can be provided with such an associated cooling device that employs liquid coolant without the need to alter the first fluid side of the heat exchanger in a way which would increase the first fluid side pressure drop.
In an exemplary embodiment of the heat exchanger described herein, the liquid coolant side of the heat exchanger can increase the amount of heat removed from the first fluid (for example, charge air) as compared to an all air-cooled heat exchanger since the first fluid is partially cooled by the liquid coolant which can be water.
In some embodiments of the present heat exchanger constructed for use as a charge air cooler, the associated cooling device that circulates the liquid coolant can desirably be located in a relatively inexpensive manner to an area or region of the heat exchanger which may be or is considered to be an air flow “dead zone”, thus permitting good heat exchange in this area despite the clear or perceived difficulty of air cooling this area.
It is further desirable to provide the aforementioned heat exchanger withan associated cooling device that uses liquid coolant in an exemplary embodiment without the need to provide complex manifolding as well in order to deliver the liquid coolant to the associated cooling device and remove liquid coolant therefrom.